CDC map of east Africa, areas with confirmed and probable cases of Ebola

The largest known outbreak of the lethal Ebola virus in West Africa is prompting authorities as far away as Asia to take preventive measures, although scientists say a global spread of the disease is unlikely.

At South Korea's Incheon International airport, a major hub for air travel in Asia, quarantine inspections of arriving passengers are being enhanced.

Screening passengers

Authorities say all passengers are being recorded by an infrared camera to detect fevers.

South Korea Foreign Ministry spokesperson Han Hye-jin says this is being done because Ebola is becoming a big concern.

She says the South Korean government, in association with health authorities, is paying attention and carefully determining if additional measures are needed.

The country's Centers for Disease Control and Prevention says it established an Ebola task force in April and is prepared for possible infections in South Korea.

Citizens urged to avoid affected countries

It is also urging South Koreans not to visit the affected African countries.

Australia is also cautioning against travel to Guinea, Sierra Leone and Liberia.

Australia's chief medical officer, Chris Baggoley, says the possibility of Ebola arriving there is "very low." But all border protection agencies are on alert for possible symptoms in people arriving by air or sea.

Dr. Nicholas Day, director of the Mahidol Oxford Tropical Medicine Research Unit in Bangkok, says these enhanced port screenings, implemented in Asia during previous swine and bird flu scares, are no panacea.

"It hasn't really, to my knowledge, been conclusively proven that it's an effective public health measure. It makes people feel happier that something is being done. But remember that people with flu, for example, don't have to be symptomatic when they come through. If you're screening using an infrared camera for temperature detection it doesn't necessarily pick up people who are infected. The same is true for Ebola," said Day.

Incubation: 2 - 21 days

The incubation period of the Ebola virus is between two and 21 days, during which time an infected person might not show any signs of infection.

In Hong Kong, the Center for Health Protection says public hospitals will begin to report and test all those who developed fever who, within the past 21 days, traveled to the three affected African countries.

Although there are no direct flights from west Africa to Hong Kong, the city's health minister, Dr. Ko Wing-man, expresses concern that infections could still enter the region via a plane flight.

Quarentine suspected cases

Hong Kong's health minister issued the warning following an emergency meeting held with specialists to discuss contingency plans should there be an outbreak there, some 13,000 kilometers from west Africa.

Ko says, "suspected cases will be put into isolation as soon as they are identified."

The city has seen one scare, so far. A 39-year-old Hong Kong woman, who recently traveled to Kenya, was placed in isolation at Queen Elizabeth's hospital after vomiting and developing a fever. Hong Kong's Hospital Authority says she tested negative for the virus and has been released.

Health Minister: low public risk

Singapore's health ministry is urging the public there "not to be alarmed." It has issued a statement deeming Ebola to pose "a low public health risk to Singapore," in part because "there is low travel connectivity to West Africa where the current outbreak remains limited to."

Singapore's Chiangi Airport is ranked the world's fifth busiest with more than 52 million passengers in 2013.

Suvarnabhumi, just outside Bangkok, is one of the world's busiest airports with more than 30 million passengers passing through every year. Thai officials say only 30 to 50 persons per week are believed to come from the countries with the current Ebola outbreak.

So far, no special screenings for Ebola among incoming passengers are being implemented. But all hospitals in Thailand are being ordered to monitor patients for any related symptoms, particularly those who have traveled to the outbreak area.

Spreaded by direct contact with bodily fluids

Some airlines have suspended flights into the affected region. But health authorities say there is little risk of passengers contracting the virus on a flight from an infected person.

Dr. Day, a tropical medicine researcher, explains Ebola is only spread through direct contact with blood, saliva and other bodily fluids.

"The reason why everyone is scared about this, and I think quite reasonably so, is that this is a particularly horrible disease. It's luckily quite difficult to transmit unless you're in actual physical contact with a patient. So with standard public health and clinical isolation, quarantine measures, it should be possible to contain any outbreak," said Day.

Since March, there have been more than 1,200 confirmed Ebola cases in West Africa. This is believed to be a new strain of the virus and nearly 700 of those infected in this worst-known outbreak have died.

Liberia is quarantining some communities, closing all schools and some markets while placing all non-essential government personnel on 30-day leave. Public gatherings have already been banned.

Sierra Leone's president, declaring a public health emergency on Thursday, called on security forces to enforce quarantine measures to prevent a further spread of infections.

No known cure

There is no known cure for Ebola. It was first recognized in Zaire (now the Democratic Republic of Congo) in 1976. There is no approved vaccine, but at least four are under development.

Ebola is a hemorrhagic fever with a fatality rate in human of up to 90 percent. It primarily occurs in remote villages in central and western Africa, near tropical rain forests. The virus is transmitted to people from wild animals. Fruit bats are considered to be the virus' natural host.